It’s the year 2040 in Japan. After decades of steady population decline, the government had finally had enough. Birth rates plummeted, marriages were rare, and the dream of “a happy household” had faded into nostalgic fiction. But the solution they came up with wasn’t just bold—it was controversial. Welcome to the “Future Compatibility Program”, a nationwide policy rolled out across select high schools. Starting second semester of freshman year, every student is evaluated based on their academic performance, psychological profiling, extracurricular interests, and behavioral tendencies. From there, they are partnered with a fellow classmate, assigned an apartment located near the school, and enrolled into a Marriage Simulation Curriculum. The mission? Develop the emotional intelligence, communication skills, and domestic compatibility required to maintain a long-term relationship. The twist? You must simulate married life with your assigned partner. Each shared apartment has two separate bedrooms (secured by individual thumbprint locks), but everything else—from cooking and cleaning to daily cooperation—is communal. The living room is monitored 24/7 by a single camera that feeds directly to the school’s Affection Tracking System. Students earn Affection Points by completing couple-like tasks, supporting one another, or simply demonstrating genuine connection. Affection Points determine your Couple Rank:

• F Rank: 0–9 points – “Cold Strangers”
• E Rank: 10–19 points – “Barely Acquainted”
• D Rank: 20–29 points – “Getting Along”
• C Rank: 30–39 points – “Functioning Duo”
• B Rank: 40–49 points – “Potential Pair”
• A Rank: 50+ points – “Ideal Couple” Only at A Rank do students gain the right to request a partner swap, but only if all parties consent. Effort is everything. Affection Points are painfully slow to earn, but easy to lose. A missed meal together, a cold argument, or even a sarcastic comment can drop your score. The goal? Reach graduation having experienced a fully immersive relationship, so when you choose a lifelong partner afterward, it’s from a place of understanding—not fantasy. Now, most students get paired with someone… manageable. Maybe even sweet. Others land lucky with a close friend or longtime crush. But unfortunately for you, you were matched with the one person on campus who looked like he’d rather set the whole program on fire than participate. Kento Maruojima. Known for his unnaturally perfect grades and a reputation that screamed “don’t talk to me,” Kento was as much a mystery as he was a menace. Always either absent, getting into fights, or dragged into the counselor’s office for another stern warning, his presence on the top of the academic leaderboard was baffling. He rarely smiled, never apologized, and certainly didn’t strike anyone as "husband material." And yet, there he was. When you opened the door to your new apartment, the air smelled faintly of burnt tobacco. You looked up—and there he was, leaning on the balcony railing, a cigarette between his fingers, exhaling smoke into the wind like it owed him something. This was your life for the next 2 and a half years. Welcome to the Marriage Simulation.